Flue Gas Treatment Device with Wet State Processing for SO3 Control
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Solution Overview
Problem
Current flue gas treatment technologies face challenges in accurately measuring and managing the fluctuating concentration of sulfur trioxide (SO3) in flue gas, leading to inefficient SO3 removal, increased maintenance costs, and economic disadvantages due to excessive use of active carbon for mercury removal.
Innovation Solution
A flue gas treatment device that includes an NOx removal unit, air preheater, precipitator, gas-liquid contact type desulfurization unit, and a wet state processing unit, which supplies water to the flue gas to create a temperature gradient, enhancing the chemical reaction of SO3 removal using agents like calcium carbonate, and optionally includes Hg removing agents and ash recycling to optimize SO3 and mercury removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If excessive amount of CaCO3 is sprayed relative to assumed SO3 concentration, then SO3 removal is ensured under high concentration conditions, but useless cost is invested when SO3 concentration is lower than assumption
Solution Approach 1:
The patent employs online SO3 concentration measurement using a laser-based differential absorption spectroscopy system that continuously monitors flue gas composition. This real-time feedback enables dynamic adjustment of CaCO3 spray rate to match actual SO3 concentration, ensuring reliable removal while avoiding excessive consumption during low concentration periods
Solution Approach 2:
The system transitions from static, assumption-based chemical dosing to dynamic, measurement-based control. The CaCO3 spray rate is continuously adjusted based on real-time SO3 concentration data, allowing the system to adapt to fluctuating operating conditions and optimize the balance between removal effectiveness and chemical consumption
2Adaptability or versatility
If SO3 concentration is increased beyond assumption by fluctuation of plant operating conditions, then more SO3 removal capacity is needed, but a SO3 removal property is deteriorated owing to shortage of chemical agent
Solution Approach 1:
The online measurement system provides continuous monitoring of SO3 concentration, enabling the control system to detect increases beyond assumed levels and immediately increase CaCO3 spray rate accordingly, maintaining removal effectiveness under varying operating conditions
Solution Approach 2:
The system maintains readiness to adjust chemical dosing by continuously measuring SO3 concentration, allowing proactive response to concentration increases before they cause removal deficiencies, rather than reacting to problems after they occur
3Reliability
If active carbon is sprayed to remove mercury, then mercury removal is achieved, but consumption amount of active carbon is largely increased in the case where concentration of coexisting SO3 is high
Solution Approach 1:
The patent extracts and removes SO3 from the flue gas stream using targeted alkaline neutralization before the mercury removal stage. By eliminating SO3 interference upstream, the active carbon can focus on mercury removal without being consumed by competing reactions, significantly reducing active carbon consumption while maintaining mercury removal effectiveness
Solution Approach 2:
The system performs preliminary SO3 removal before mercury removal to prevent SO3 from interfering with active carbon's mercury adsorption capacity. This sequential approach ensures that active carbon is not wasted on neutralizing SO3, thereby reducing overall consumption while maintaining reliable mercury control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The device effectively manages SO3 concentration fluctuations by accelerating chemical reactions on the surface of SO3 removing agents, reducing the amount of agents needed, minimizing costs, and improving the efficiency of SO3 and mercury removal, thereby reducing maintenance and operational expenses.
Implementation Method 1
supplies water to the flue gas to create a temperature gradient, enhancing the chemical reaction of SO3 removal using agents like calcium carbonate
Implementation Method 2
enhancing the chemical reaction of SO3 removal using agents like calcium carbonate
Data Source
AI summary
Provided are: an NOx removal unit to remove nitrogen oxide; an air preheater on a downstream side of the NOx removal unit to recover heat; a precipitator on a downstream side of the air preheater to remove ash dust; a gas-liquid contact type desulfurization unit on a downstream side of the precipitator to remove sulfur oxide; an SO3 removing agent supply unit to supply an SO3 removing agent at a supply unit on an upstream side of the precipitator; and a wet state processing unit between the air preheater and the supply unit to supply water to a flue gas to be made into a wet state; the wet state processing unit having a stand-up portion, a partition unit and a droplet supply unit.